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i'm on a roll... the kgsshv


kevin gilmore
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Those that were following my BOM need to make sure to use an isolation pad on the +/-15V regulators. Or substitute the units with 511-L7815CP and 511-L7915CP. On the negative rail, the tab is connected to the input pin, so the input could potentially short to the ground if isolation pads are not used... Really sorry about this.

I would not use ST Micro regulators... I've had problems with them in the past, mostly the negative, Use Fairchild or National or ON instead.

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^ the one I recall was in a circuit (don't remember what it was exactly) that wouldn't draw enough current for the negative regulator to go into regulation. Increased the load and it would regulate. Replaced with a Fairchild (and then an ON) and both worked perfectly.

EDIT: remembered what it was in: a dynahi board (+/- 15V regs for the servo opamps). 1 opamp would not pull enough current to convince the STM neg regulator that it should, umm, regulate. No problems with the other brands mentioned.

Edited by Pars
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put a load on it before you throw it away...

I know about the load and was absolutely sure that I tested it under the load. As you can see it’s the original KGBH board and not KGSSHV but the + 15/-15v sections are almost identical so it should not matter really in my case.

To make long story short I was having problems with the amp board which eventually lead to problems with PSU. My old 7915 regulator, do not even remember which manufacturer, was working fine there before I screw it up. So after trying STMs I thought that my input voltage a bit high for this particular regulator. I am really glad to look dumb stupid now facepalm.png , if not this thread I would put the project on hold again. Now everything looks like working right, all I need is to find time to powder coat my panels and put this beast together. 000-dancing.gif

IMG_4227.jpg

Edited by vvs_75
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I finished the wiring today. Balance and Offset are within 1 V on both sides.

Problem is, there is volume only on the right side even with the volume down to zero, then it sounds equal on both sides as the pot is increased to about 12 o'clock undecided.gif

Because there is eventually sound on both sides I figure the connections are fine; since the balance and offset are fine, sound like the amp is fine too.

I did not ground the Pot.

Checked all the connections, I flipped the O- and O+ because of the flipped feedback.

I am thinking is the Khozmo. Not sure yet.

Edited by eggil
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Arghh yeah ok.

The only other thing could be where Arek has joined the wires together, I asked for 400mm length wires, thinking that it would be one piece of wire directly from inside the attenuator, instead he just extended it by soldering and heat shrinking a new piece of wire.

So maybe the join is cold?

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is one single wire. I opened it and all are soldered to the boards. I am stumped and will have to return it.

We'll see how good their customer service is.

I now get OL on all the stacks, but when I measure the In and Out on the same stack get 51K (I have the 50K pot).

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How are you measuring them eggil?

I believe 2 wafers control one channel (either right or left). Each XLR channel has hot and cold. Hot to one wafer and cold to the other wafer. One wafer will have "in", "out" and "ground". "In" will connected to the XLR and "out" to amp input. To check if the wafer/attenuator is working correctly measure the "in" and "out".

Edited by Victor Chew
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That's how I am measuring them; I get an open line (OL) from all of them now, when measuring In from one wafer to Out to the other wafer.

If unable to fix I think I may try the Goldpoint instead. Too bad it has only 23 steps, but I have found myself using the share screen in another computer to fiddle with the iTunes volume anyway.

Edited by eggil
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Threw in a 3A fuse. No problem. regulates at 506V. Very Solid.

Edit: Tested the negative postive rail separately. No problem. Solid regulation at +506V. Bias is very stable at 480V. Today is a happy day. smile.png

Edited by ujamerstand
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Bias ought to be 580v instead of 480v.

A need to use at least 3A fuse for the PS alone looks like it is pulling quite a lot of current. I am using a 2A with amp connected to the PS and source playing through the amps. Nevertheless, congratulations on get the PS up.

Edited by Victor Chew
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